JPH1046160A - Method for fluidized bed catalytic cracking of heavy oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved method for the fluidized bed catalytic cracking of a heavy oil which can provide a high yield of a heavy oil fraction and high yields of gasoline and low-boiling olefins. SOLUTION: In the first fluidized bed catalytic cracker having a regeneration zone, a reaction zone, a separation zone and a stripping zone, a heavy oil is brought into contact with a catalyst under conditions in which the temperature at the exit of the reaction zone is in the range of 450-550 deg.C. In the second fluidized bed cracker having a regeneration zone, a reaction zone, a separation zone and a stripping zone, the heavy decomposition product obtained in the first cracker is brought into contact with a catalyst under conditions in which the temperature at the exit of the reaction zone is in the range of 550-750 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a fluid catalytic cracking (FCC) method for heavy oil. In particular, the present invention relates to a fluid catalytic cracking method for catalytic cracking of heavy oil to obtain gasoline and light olefins such as ethylene, propylene, butene, and pentene.

[0002]

2. Description of the Related Art In general catalytic cracking, petroleum hydrocarbons are decomposed by contact with a catalyst, and gasoline as a main product is produced.
A small amount of LPG and cracked light oil are obtained, and the coke deposited on the catalyst is burned and removed with air to reuse the catalyst by circulation.

However, recently, there has been a movement to utilize a fluid catalytic cracking unit not as a gasoline production unit but as a light olefin production unit as a petrochemical raw material. The use of such a fluid catalytic cracker has particular economic advantages in refineries where petroleum refining and petrochemical plants are highly linked.

As a method for producing a light olefin by fluid catalytic cracking of heavy oil, for example, a method of shortening the contact time between a catalyst and a feed oil (US Pat. No. 4,419,221;
U.S. Pat. No. 3,074,878, U.S. Pat.
652, EP 315,179A), a method of performing the reaction at a high temperature (US Pat. No. 4,980,053),
Method using pentasil-type zeolite (US Pat.
26, 465, Publication No. 7-506389).

However, these methods have some problems. For example, in a high-temperature reaction, thermal cracking of heavy oil occurs simultaneously, and the dry gas yield increases. In addition, the reaction at high temperature increases the concentration of dienes in gasoline,
In order to use this gasoline as fuel for automobiles, post-treatment is required.

On the other hand, the method of shortening the contact time can suppress the hydrogen transfer reaction and reduce the rate of conversion of light olefins to light paraffin, but reduce the yield of heavy oil fraction of low utility value. Can not.

In the method using a pentasil type zeolite, the gasoline fraction produced is overcracked to increase the yield of light olefins, so that the gasoline yield is sacrificed.
Therefore, it is difficult to obtain light olefins and gasoline from heavy oil in high yield by these single techniques.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved fluid catalytic cracking method for heavy oil having a low yield of heavy oil fraction and a high gasoline and light olefin yield. .

[0009]

The present inventors have found that the object can be achieved by combining ordinary heavy oil fluid catalytic cracking with severe heavy oil fluid catalytic cracking. The present invention is based on the present invention.

[0010] That is, the fluid catalytic cracking method for heavy oil of the present invention comprises a first fluid catalytic cracking reactor having a regeneration zone, a reaction zone, a separation zone and a stripping zone.
The heavy oil is brought into contact with the catalyst at a reaction zone outlet temperature of 450 ° C. or more and 550 ° C. or less, and then the heavy cracked product obtained in the first fluid catalytic cracking reactor is converted into a regeneration zone, a reaction zone, Second with separation band and stripping band
Wherein the catalyst is brought into contact with the catalyst in a reaction zone outlet temperature range of more than 550 ° C. and 750 ° C. or less.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail.

In the present invention, heavy oil is used as a feedstock oil. As the heavy oil, a heavy oil containing a fraction having a boiling point range of 250 ° C. or more at normal pressure of 70% or more, preferably 80% or more is preferable. For example, straight-run gas oil (LGO, HGO), vacuum gas oil (VGO), atmospheric residue, vacuum residue, pyrolysis gas oil,
Alternatively, a heavy oil obtained by hydrorefining them or the like can be exemplified. These heavy oils may be used alone, or a mixture of these heavy oils or a mixture of these heavy oils and a partly light oil may be used.

The first fluid catalytic cracking reactor used in the present invention is an ordinary heavy oil fluid catalytic cracker having a regeneration zone, a reaction zone, a separation zone and a stripping zone.

In the reaction zone, the above-mentioned heavy feedstock is brought into continuous contact with a catalyst maintained in a fluidized state, and the heavy feedstock is decomposed into light hydrocarbons mainly composed of gasoline. This contact may be performed by a fluidized bed of the catalyst, or may employ so-called riser-cracking in which both the catalyst particles and heavy oil rise in the tube. The mixture of the cracked product and the catalyst thus obtained by the catalytic cracking is sent to a separation zone, where the catalyst and the cracked product are separated. The catalyst with the carbonaceous and partially heavy hydrocarbons attached is sent to a stripping zone, where the oil attached to the catalyst is removed. The catalyst exiting the stripping zone is sent to a regeneration zone (regeneration tower). Then, in the regeneration zone, an oxidation treatment of the catalyst to which the carbonaceous material is attached is performed. The catalyst that has been subjected to this oxidation treatment is a regenerated catalyst, in which carbonaceous materials and hydrocarbons deposited on the catalyst have been reduced. This regenerated catalyst is continuously circulated to the reaction zone.

In the present invention, the reaction zone outlet temperature refers to the outlet temperature of a fluidized bed type reaction tower (reaction zone). In the present invention, in the first fluid catalytic cracking reactor, heavy oil is decomposed at a reaction zone outlet temperature of 450 ° C. or more and 550 ° C. or less, preferably 480-530 ° C. If the temperature is lower than 450 ° C., not only the gasoline yield decreases, but also the octane number of gasoline decreases, which is not preferable. 550 ° C
At a higher temperature, the produced gasoline fraction is excessively cracked, and the gasoline yield is lowered, and the diene value of the produced gasoline is undesirably increased.

The conditions other than the reaction zone outlet temperature of the first fluid catalytic cracking reactor in the present invention are as follows. The temperature of the regeneration zone catalyst rich phase is preferably between 650 and 8
00 ° C, more preferably 670-750 ° C. The reaction pressure is preferably 1 to 3 kg / cm ² G, the feed oil preheating temperature is preferably 100 to 300 ° C., and the catalyst / oil ratio is preferably 4 to 10 wt / wt.

In the present invention, heavy oil is cracked in the first fluid catalytic cracking reactor, and this cracked product is fractionated into the following fractions in an atmospheric distillation column. The typical yields of each fraction are as follows.

[0018]

[Table 1]

In the present invention, the heavy decomposition product is LC
O and / or HCO ⁺ , which is the feedstock for the second fluid catalytic cracking. LCO has an initial boiling point of 150-23
It is a fraction having a boiling point range of 0 ° C and an end point of 300 to 370 ° C.
HCO ⁺ is a fraction having a boiling point range of an initial boiling point of 300 to 370 ° C. and an end point of 500 ° C. or more, and includes heavy cycle oil (HCO),
It consists of decanted oil (DCO) and slurry oil. DCO is a supernatant oil from which the bottom oil of the distillation column is separated by standing in a stationary tank to remove the catalyst, and a slurry oil is a precipitated oil containing fine catalyst particles.

In the present invention, the heavy cracked product obtained by cracking in the first fluid catalytic cracking reactor, ie, L
The CO or HCO ⁺ alone or as a mixture, and the HCO ⁺ further fractionated HCO and DCO alone or as a mixture are then decomposed in a second fluid catalytic cracking reactor. The second fluid catalytic cracking reactor used in the present invention is also a heavy oil fluid catalytic cracking device having a regeneration zone, a reaction zone, a separation zone and a stripping zone as in the first fluid catalytic cracking reactor, A quenching section for the decomposition product may be provided after the reaction zone outlet.

Since the heavy oil cracking product obtained by cracking in the first fluid catalytic cracking reactor has low reactivity, in the present invention, the temperature of the reaction zone outlet is 5 in the second fluid catalytic cracking reactor.
More than 50 ° C. and 750 ° C. or less, preferably 580 to 720
Decomposed at ℃. If the reaction zone outlet temperature of the second fluid catalytic cracking reactor is 550 ° C. or lower, it is not preferable because a sufficient conversion (raw material → decomposition product) cannot be obtained. If the temperature at the outlet of the reaction zone is higher than 750 ° C., the amount of dry gas generated by the thermal decomposition of the feed oil increases, and the amount of coke generated remarkably increases.

As described above, since the second fluid catalytic cracking reactor is operated at a higher temperature, the contact time between the oil and the catalyst in the reaction zone is preferably shorter, for example, preferably 2 seconds or less, and more preferably 0.1 second or less. Five seconds are employed. The contact time refers to the time from contact between the regenerated catalyst and the feed oil until the catalyst and decomposition products are separated at the reaction zone outlet, or the time until rapid cooling in the case of rapid cooling before the separation zone. . Although the type of the reaction zone is not limited, a downflow type reactor is preferably employed because of such a short contact time.

The conditions other than the reaction zone outlet temperature of the second fluid catalytic cracking reactor in the present invention are as follows. The temperature of the regeneration zone catalyst rich phase is preferably between 650 and 8
00 ° C, more preferably 670-750 ° C. The reaction pressure is preferably 1 to 3 kg / cm ² G, the feedstock preheating temperature is preferably 100 to 450 ° C., and the catalyst / oil ratio is preferably 15 to 50 wt / wt.

In the present invention, the heavy cracked product obtained by cracking in the first fluid catalytic cracking reactor is cracked in the second fluid catalytic cracking reactor, and the cracked product is separated by the atmospheric distillation column. Fractionate into the following fractions: The typical yields of each fraction are as follows.

[0025]

[Table 2]

As the catalyst used in the first and second fluid catalytic cracking reactors of the present invention, a catalyst containing a zeolite and an inorganic oxide matrix component usually used in a fluid catalytic cracking reactor can be used.

Examples of the zeolite include natural zeolites and synthetic zeolites. Examples of natural zeolites are gmelinite, shabasite, dakiardofluorite, clinoptilolite, faujasite, kifuite, hoofite,
Examples include lepinite, erionite, sodalite, canclinite, ferrierite, bridgester fluorite, offretite, soda fluorite, mordenite, and the like.
These may be used alone or in combination. Of these, faujasite is preferred. X, Y, A, L, ZK-4, B, E, F, H
J, M, Q, T, W, Z, Alpha, Beta, ZSM
And omega-type zeolites. These may be used alone or in combination. Of these, Y-type zeolites and X-type zeolites are preferred. An ultra-stable Y type having a lattice constant of 2.425 to 2.460 nm obtained by dealumination of a Y type zeolite (US
Y) Zeolites are more preferred.

Examples of the inorganic oxide matrix component include clays such as kaolin, montmorillonite, halloysite, and bentonite; and inorganic porous oxides such as alumina, silica, boria, chromia, magnesia, zirconia, titania, and silica-alumina.

The content of zeolite, which is the active component of the catalyst used in the present invention, is preferably 5 to 60% by weight, more preferably 15 to 40% by weight.

The catalyst used in the present invention has a bulk density of 0.5 to
1.0 g / ml, average particle size 50-90 μm, surface area 50-400 m ² / g, pore volume 0.05-0.5 m
Those in the range of 1 / g are preferred. The catalyst used in the present invention can be produced by a usual production method.

[0031]

EXAMPLES Next, the present invention will be described based on examples and the like, but the present invention is not limited to these examples.

(Example 1) VGO was used as a raw material oil by FCC
It was decomposed by a commercial apparatus (first fluid catalytic cracking reactor), and DCO of the obtained heavy decomposition products was decomposed by an adiabatic riser-type FCC pilot apparatus (second fluid catalytic cracking reactor).

The first fluid catalytic cracking reaction device (the device scale is
Inventory (catalyst amount) 200 tons, feed amount 3
The operating condition of the reaction zone was 7000 BPD).
95 ° C., catalyst / oil ratio 5 wt / wt, regeneration zone catalyst rich phase temperature 670 ° C., reaction pressure 1.0 kg / cm ² G,
The contact time is 5 seconds.

The second fluid catalytic cracking reaction device (the device scale is
(Inventory-2 kg, feed rate 1 kg / h) operating conditions are as follows: reaction zone outlet temperature 680 ° C, catalyst / oil ratio 3
0 wt / wt, regeneration zone catalyst dense phase temperature is 750 ° C., reaction pressure is 1.0 kg / cm ² G, and contact time is 0.4 second.

VGO, which is the feed oil for the first fluid catalytic cracking reactor, and DC, which is the feed oil for the second fluid catalytic cracker.
Table 3 shows the properties of O. The catalyst used in the second fluid catalytic cracking reactor is Octact catalyst (manufactured by WR GRACE).

The catalyst used in the second fluid catalytic cracking reactor is the equilibrium catalyst used in the first fluid catalytic cracking reactor.

Table 4 shows the reaction results obtained by the first and second fluid catalytic cracking reactors, respectively. The first and second
Table 4 also shows the product yield when both the results of the fluid catalytic cracking reactor were combined.

(Comparative Example 1) Catalytic cracking was carried out using the same apparatus, feedstock, catalyst and conditions as in Example 1 except that the operating conditions of the second fluid catalytic cracking reactor of Example 1 were changed as follows. .

The operating conditions of the second device were a reaction temperature of 500 ° C.
Catalyst / oil ratio 7 wt / wt, regeneration zone catalyst rich phase temperature 7
00 ° C., reaction pressure 1.0 kg / cm ² G, contact time 0.4 seconds.

Table 5 shows the reaction results obtained by the first and second fluid catalytic cracking reactors, respectively. The first and second
Table 5 also shows the product yield when both the results of the fluid catalytic cracking reactor were combined.

[0041]

[Table 3]

[0042]

[Table 4]

[0043]

[Table 5]

As is clear from the above results, the cracking of the present invention in which the uncracked oil obtained from the first fluid catalytic cracking reactor is cracked at a high temperature (680 ° C.) using the second fluid catalytic cracking reactor. The method was able to increase the yield of light olefins and significantly reduce the bottom yield.

[0045]

According to the fluid catalytic cracking method for heavy oil of the present invention, the yield of heavy oil fraction can be reduced and the yield of gasoline and light olefin can be increased.

Claims (2)

[Claims] In a first fluid catalytic cracking reactor having a regeneration zone, a reaction zone, a separation zone and a stripping zone, heavy oil is mixed with a catalyst at a reaction zone outlet temperature of 450 ° C. or more and 550 ° C. or less. And contacting the heavy cracked product obtained in the first fluidized catalytic cracking reactor with a reaction zone in a second fluidized catalytic cracking reactor having a regeneration zone, a reaction zone, a separation zone and a stripping zone. A fluid catalytic cracking method for heavy oil, wherein the catalyst is brought into contact with the catalyst at an outlet temperature of from 550 ° C to 750 ° C. 2. The fluid catalytic cracking method for heavy oil according to claim 1, wherein the catalyst contains zeolite.